•Heterofermentative microbial inoculation improves aerobic stability after short-term fermentation.•Forage sorghum had greater starch disappearance than sorghum sudan.•Prolonged storage length increased proteolysis and starch disappearance of both cultivars. In recent years, the interest to grow sorghum for silage has increased, with greater prominence in areas where water supply and or availability is an issue for plant growth. Therefore, the objective of this study was to evaluate the effects of sorghum cultivars (forage or sudan), storage length and microbial inoculation with heterofermentative and facultative homofermentative inoculants on the fermentation profile, DM loss, aerobic stability and ruminal in situ starch disappearance of whole-plant sorghum silage. Whole-plant sorghum (279 ± 37 g/kg DM for forage and 232 ± 29 g/kg DM for sudan) was ensiled in quintuplicate 20 L plastic buckets untreated (CON) or after the following treatments: Lactobacillus plantarum CH6072, L. plantarum LSI, and Pediococcus pentosaceus P6 at 1 × 105 cfu/g of fresh forage (LPPP); L. buchneri LB1819 and Lactococcus lactis O224 at 1.5 × 105 cfu/g (LBLL). Silos were allowed to ferment for 0, 15, 30 or 90 d. Lactic acid and total acids were greatest in sudan sorghum silage, and total acids were greatest in LPPP and lowest for LBLL. Ammonia-N (as g/kg of total N) was greatest with sudan sorghum. The acetic acid was greatest in forage sorghum inoculated with LBLL, intermediate in sudan sorghum inoculated with LBLL, and linearly increased in both cultivars with storage length from 15 to 90 d. Silage aerobic stability was greater for LBLL compared to CON and LPPP. Ruminal in situ starch disappearance was increased with ensiling time, and linearly increased from d 15–90. Microbial inoculation with L. buchneri and Lactococcus lactis increased the acetic acid concentrations, improved aerobic stability, and reduced the DM loss by discarded visible spoilage, at the expense of higher DM loss by gases. This effect was more evident in forage sorghum compared to sudan sorghum.